Crater Chains

The large crater at the top of this THEMIS visible image has several other craters inside of it. Most noticeable are the craters that form a "chain" on the southern wall of the large crater. These craters are a wonderful example of secondary impacts. They were formed when large blocks of ejecta from an impact crashed back down onto the surface of Mars. Secondaries often form radial patterns around the impact crater that generated them, allowing researchers to trace them back to their origin.